Created By : Rina Nayak

Reviewed By : Phani Ponnapalli

Last Updated : Apr 03, 2023

Osmotic Pressure Calculator analyzes the amount of pressure required to completely halt the osmosis. Just give the number of ions, osmotic coefficient, concentration, and temperature in the specified input fields and click the calculate button to get the exact osmotic pressure value in the output section.

Number of ions
Osmotic coefficient
Osmotic pressure

Steps to Find Osmotic Pressure

The below-included are the steps to compute the osmotic pressure of a chemical solution. Use these techniques to check the result in a fraction of seconds.

  • Note down the dissociation factor, osmotic coefficient of the solute, solution molar concentration, universal gas constant and temperature.
  • Bring all these values into the same unit.
  • Multiply each and every value.
  • The obtained product is the osmotic pressure.

Osmotic Pressure Definition

Osmosis is a process where the molecules of the solvent flow from the solution of low concentration to the solution of high concentration through a semipermeable membrane. Any solvent can undergo an osmosis process including gases and supercritical liquids. The two main types of osmosis are endosmosis and exosmosis.

The osmotic pressure is the minimum pressure that needs to be applied to halt the flow of solvent molecules from the dilute solution to the concentration solution using a semipermeable membrane called osmosis. Applying such pressure allows the solution to reach the osmotic equilibrium. This osmotic pressure process is applied in many chemical and industrial processes like water desalination, water purification and waste mineral treatment.

Osmotic Pressure Equation and its Coefficients

The formula of osmotic pressure is mentioned-here.

osmotic pressure formula

The below-given table gives the osmotic pressure coefficient for the common substances.

Solution Number of ions obtained by dissociation n Molecular weight M Osmotic Coefficient Φ
NaCl 2 58.5 0.93
KCl 2 74.6 0.92
HCl 2 36.6 0.95
NH₄Cl 2 53.5 0.92
NaHCO₃ 2 84 0.96
NaNO₃ 2 85 0.9
KH₂PO₄ 2 136 0.87
CaCl₂ 3 111 0.86
MgCl₂ 3 95.2 0.89
Na₂SO₄ 3 142 0.74
K₂SO₄ 3 174 0.74
MgSO₄ 2 120 0.58
Glucose 1 180 1.01
Sucrose 1 342 1.02
Maltose 1 342 1.01
Lactose 1 342 1.01


Question: The osmotic pressure of a potassium chloride solution (at 300K) is 50 atmospheres. What is the molar concentration of potassium chloride in this solution?


Given that

Temperature T = 300K

Osmotic pressure π = 50 atm

The molar concentration of the solution c = π/(n * Φ * R * T)

c = 50/(2 x 8.314 x 0.0821 x 300)

= 50/49.26

= 1.015 M

Therefore, the molar concentration of the potassium chloride is 1.015 M.

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Frequently Asked Question's on Osmotic Pressure Calculator

1. What is the osmotic pressure formula?

The osmotic pressure equation is π = n * Φ * c * R * T. Here, π is the osmotic pressure, n is the number of ions, Φ is the osmotic coefficient of the solute, c is the concentration of the solution, R is the gas constant, and T is the temperature.

2. How to calculate the osmotic pressure?

The simple steps to find the osmotic pressure are along the lines:

  1. Choose a solute to analyze
  2. Get the values of dissociation factor, molecular weight and osmotic coefficient
  3. Check the temperature of the environment in which osmosis takes place.
  4. Find the molar concentration of the solution i.e c = m/(M x V)
  5. Substitute all these values in the formula of osmotic pressure to get the answer.

3. What is the osmotic pressure and example?

The osmotic pressure is defined as the minimum pressure that should be applied to stop the flow of solvent molecules through a semipermeable membrane. An example of osmotic pressure is plants maintain their upright shape by using it.

4. What is Osmosis?

If you separate a dilute solution from the concentrated solution of the same type by a membrane, then the solvent molecules move from the dilute solution to the concentrated solution. This movement continues until it reaches an equilibrium state. This flow of solvent molecules due to the difference in concentration is called osmosis.

Osmotic Pressure Calculator